This invention relates to a heat transfer recording device which performs color and monochrome heat transfer recording, and more particularly to printing control based on binary and multi-valued data.
FIG. 1 is a perspective view showing an outline of the structure of an example of the conventional heat transfer color recording device. It illustrates a device known as plane sequential swing type. In the figure, the recording head (thermal head) 1 has a plurality of heating resistors (printing elements) lined up in the main scanning direction. It performs transfer recording. Paper 4 moves from paper roll 3 in the direction indicated by arrow A (secondary scanning direction) pressed by pressure roll 8. Ink ribbon 7 moves from supply roll 5 to take-up roll 6 in conjunction with the movement of a record carrier or paper 4, between recording head 1 and platen 2. This recording head 1 performs transfer recording while being pressed against platen 2 by spring 14 fixed to a protrusion of bracket 12 which supports recording head 1, with support point 13, which is attached to bracket 12, as its rotational center.
The width of ink ribbon 7 is almost the same as that of paper 4. It has tri-base-color (yellow, magenta, cyanogen) transfer printing inks applied in plane order to application areas 7b on base film 7a. Each application area 7b has a dimension L' just a bit larger than dimension L of the transport direction of recording area 9 established beforehand on paper 4. In other words, as shown in FIG. 1, transfer inks are applied to ink ribbon 7 in order to color for rectangular application areas 7b on base film 7a. Marks or indicia 10a, 10b and 10c corresponding to the print beginning positions of respective colors of the transfer ink are printed beforehand along an edge of application areas 7b of ink ribbon 7. It is then possible for these marks to be detected by ribbon sensor 11.
Head motor 15 rotates bracket 12 about support point 13 through cam 16 to move down so that recording head 1 is separated from platen 2 during recording (printing) standby and during movement to set ink ribbon 7 at the print beginning position of each color.
In a structure such as this the following operation is performed when it has been established beforehand to record (print) in the order yellow, magenta, cyanogen.
First, when turning on the power supply, after moving ink ribbon 7 until ribbon sensor 11 has detected mark 10a corresponding to the print beginning position of yellow and positioning it there, recording head 1 is pushed towards platen 2. By moving (transporting) paper 4 and ink ribbon 7 together in the secondary scanning direction yellow transfer is performed for recording area 9. Next, after paper 4 has been sent back, with recording head 1 separated from platen 2 by motor 15, to its original position, ink ribbon 7 is moved until sensor 11 detects magenta's mark 10b and as with yellow, magenta is transferred to recording area 9 to which yellow was transferred. Then, paper 4 is move back as was done with yellow and magenta, and after mark 10c is detected, cyanogen is transferred over recording area 9. In this way color recording is performed for a single frame (recording area 9).
The ink ribbon 7 used for this kind of thermal transfer recording device is divided into the following two types according to the composition of the ink applied. There is a fusion type ink ribbon which has wax as its main ingredient and is composed of pigments, additives, and softening agents, and a sublimation type ink ribbon which is composed of sublimating disperse dye, polyvinyl alcohol, synthetic resin, and a solution such as toluene, ketone etc.
FIG. 2 shows data concerning printing density of the ink transferred to paper 4 as measured with a Macbeth density meter, with respect to the energy applied to thermal head 1. When applied energy reaches a set value the printing density increases rapidly for the fusion type ink ribbon (shown with circles). If applied energy is increased beyond this it reaches a saturated state in which printing density does not increase. On the other hand printing density is almost proportional to applied energy for the sublimation type ink ribbon (shown with triangles).
The main uses of fusion type ink ribbons are hard copies from CRT's for computer terminals performing image expression with binary data. On the other hand, sublimation ink ribbons are used mainly for full color hard copies from television screens used in broadcasting which perform image expression with multi-value data. Because of difference in print control methods, both are used with their own specialized recording devices.
However, the thermal transfer recording device structure described above contains the problem described below.
Because of the progress of CRT terminal devices, it is possible for the image to express binary and multi-value data. However, because of the differences in the respective printer control methods it is necessary to provide separate binary and multi-valve hard copy devices to connect to them.